Electric spark detonators



April 9, 1968 J. VILBAJO ELECTRIC SPARK DETONATORS Filed June 11, 1964J. V4! 1 bajo United States Patent ELECTRIC SPARK DETONATORS JeanVilbajo, Brussels, Belgium, assignor to Contigea Societe Anonyme,Brussels, Belgium Filed June 11, 1964, Ser. No. 374,537 Claims priority,application Belgium, June 18, 1963,

633,725; Apr. 23, 1964, 519,452 2 Claims. (Cl. 102-28) It is a wellknown fact that, with electric spark detonators, one of the maindifiiculties consists in providing the optimum gap between electrodes.This gap is com- .paratively very small, so that in the present state ofadvance of the technology, it is so hard to calibrate this gap with ahigh degree of precision, that this difiiculty hampers and slows downthe production of such electric detonators, frequently introduces aninsecurity factor and is certainly one of the conditions which justify acomparatively high cost price.

The electric detonators according to the present invention areessentially characterized by the fact that between both electrodes athin layer of some electric insulating material is inserted, which isessentially characterized by the fact that there is at least one holegoing right through this material and that this hole is disposed in thevicinity of the junction between one of the electrodes and aninflammable or explosive material.

The insertion of such a thickness of an insulating material rightthrough which a free passage is provided leads to a simple, economic andaccurate solution to the problem of exactly satisfying the distancecondition between electrodes. The exact position of aforesaid passage issuch that the spark which is produced at the proper time betweenelectrodes reaches for certain the combustible or explosive material.

This extremely simple and original means can be applied under manydifferent forms in order to make it adaptable to all practical cases.

It is therefore merely by way of example and without implying any kindof restriction, that some forms of embodiment are described in greaterdetail below, with reference to the appended drawings, of which:

FIGURE 1 is a diagrammatic radial cross-section of the essentialelements which are part of an electric spark detonator according to thepresent invention;

FIGURE 2 is a Cross-section "by a plane whose trace follows the straightline II-II of FIGURE 1;

FIGURE 3 illustrates in radial cross-section the essential elements ofthe invention in an application which is decidedly different from thepreceding one;

FIGURE 4 is a cross-section by a plane whose trace follows the straightline IV-1V of FIGURE 3;

FIGURE 5 illustrates in a radial cross-section a practical applicationof the design according to FIGURE 1;

FIGURE 6 is a cross-section by a plane whose trace follows the straightline VI-VI of FIGURE 5.

In the diagrammatic illustration of FIGURES l and 2, an electrode 1 ofan electric detonator for projectiles is separated from the mass 2 by aninsulating material 3. This electrode 1 lies on top of a priming mixture4 surrounded by the second electrode 5 which is in contact withaforesaid mass 2. Aforesaid priming mass 4 lays in turn on top of thesecondary charges 6. Aforesaid priming mixture 4 may be eitherconducting or not. If it is conducting, the detonator will have a lesserelectric resistance and therefore a higher sensitivity. If on thecontrary, aforesaid priming mixture is nonconducting,

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the electrical resistance of the detonator will be practically infiniteand its sensitivity considerably less.

In accordance with the main characteristic of the present invention, atleast one thickness 7 of some insulating material such as for instancepaper or mica or some synthetic resin or other is inserted between thefirst elec trode 1 and its insulating wrapping 3 on the one hand, andthe second electrode 5 and its priming load 4 on the other hand. Atleast one hole 8 goes right through this thickness 7 and is disposed inthe vicinity not only of both electrodes 15 but also of the priming load4. In the example which is illustrated diagrammatically, aforesaidchannel 8 slightly overlaps the junction between the priming mass 4 andthe second electrode 5 whilst having on top the corresponding part ofthe first electrode 1 and the insulating mas 3. The dimension of thethickness 7 determines systematically, without any difiiculty whateverand with a high degree of precision that of the interelectrode gap 1-5.On the other hand, the manufacturing of such an electric detonator isextremely easy, fast and cheap. When the electrodes 1-5 are connectedinto circuit, the spark that flashes between them must necessarily reachthe primary priming mixture 4.

The shape, the dimensions, the number of channels 8 vary according tothe intended applications, which conveys to this new means aconsiderable universality, and,

to the electric detonator, a very high degree of fidelity.

The channel or channels 8 can be made either before or after mountingthe detonator.

In the example illustrated in FIGURES 3 and 4, a very summary anddiagrammatic illustration has been given of a form of embodiment basedexactly on the same fundamental design but of very different morphologyin order to show the universal character of the invention. It showsagain the first electrode 1, the second electrode 5', the insulatinginsert 7, the channel or channels 8' which go right through aforesaidinsert and the primary priming mixture 4'. Also, in this same form ofembodiment, the channel or channels are disposed in the vicinity of thetwo electrodes and of the primary priming mixture 4'. If, in the firstexample illustrated in FIG- URES 1 and 2, the insert 7 assumed to shapeof a very thin disc, in the example of FIGURES 3 and 4, it is coiled upcylindrically.

In this way it becomes possible to adapt the object of the presentinvention to any kind of electric detonator.

Finally, by way of simple information, FIGURES 5 and 6 illustrate apractical application of aforesaid electric detonator to a primarydevice for projectiles. In this case, we recognise again the firstelectrode 1", the outer Wrapping 2" forming the mass of the detonator,the primary priming mixture 4", the second electrode 5", the secondarycharges 6"6', the insulating insert 7" with its channels 8", whichlatter in this case are two diametrically opposite openings.

For the ease of manufacturing, the two electrodes 1"5", the insulator3", the primary priming charge 4" and the inserts 7"8" are mutually heldtogether by a jacket 9" adjusted in the outer jacket 2" which forms themass.

The object of the invention is to provide the means as such, consistingin establishing with precision the interelectrode gap by means of atleast one insert of an insulating material pierced right through, atleast in one spot, by a channel disposed in the vicinity both of the twoelectrodes and of the primary priming charge, as well as all and sundryapplications of this means.

What I claim is:

1. Electric spark detonator, comprising a priming mass, a firstring-shaped electrode surrounding said mass, a second cylindricalelectrode located above said priming mass and a disc-shaped layer of anelectrically insulating material having at least one hole, said layerbeing interposed between one of said electrodes and said priming mass,on the one hand, and the other of said electrodes, on the other hand,whereby said hole establishes a path for a spark between an edge of oneof said electrodes and the other of said electrodes through said primingmass.

2. Electric spark detonator according to claim 1,

RTCHARD References Cited UNITED STATES PATENTS 5/1955 Smits 102-2812/1959 Taylor 10270.2 2/1962 Kaspaul 102-28 1/1964 Jasse 10228 7/1965McNulty et al. 10228 X FOREIGN PATENTS 4/ 1962 Canada. 10/ 1957 France.8/ 1958 France.

M. WOOD, Primary Examiner.

h r W ereln said second electrode is embedded in a mass of 1,, VOLODYMYRY. M AYEWSKY Examineran electrically insulating material.

1. ELECTRIC SPARK DETONATOR, COMPRISING A PRIMING MASS, A FIRSTRING-SHAPED ELECTRODE SURROUNDING SAID MASS, A SECOND CYLINDRICALELECTRODE LOCATED ABOVE SAID PRIMING MASS AND A DISC-SHAPED LAYER OF ANELECTRICALLY INSULATING MATERIAL HAVING AT LEAST ONE HOLE, SAID LAYERBEING INTERPOSED BETWEEN ONE OF SAID ELECTRODES AND SAID PRIMING MASS,ON THE ONE HAND, AND THE OTHER OF SAID ELECTRODES, ON THE OTHER HAND,WHEREBY SAID HOLE ESTABLISHES A PATH FOR A SPARK BETWEEN AN EDGE OF ONEOF SAID ELECTRODES AND THE OTHER OF SAID ELECTRODES THROUGH SAID PRIMINGMASS.